A fluid bed dryer is a kind of equipment which can be used for applications like drying of powders, mixing of powders and agglomeration. This is efficiently employed for applications in chemical, pharmaceutical, dyetuff, foodstuff, dairy and various other process industries. Fluid bed dryers are often employed with the spray dryers and granulation systems for effective drying, mixing, granualtion, finishing and cooling of powdered substances. These are often preferred over rotary dryers for drying and cooling a wide range of polymer materials which require precise control of residence time and temperature for effective processing.Fluid bed dryer works on a principle of fluidization of the materials. In fluidization process, hot air or gas flow is introduced through the bed of solid particulates. This gas or air will move upwards through the spaces between the particles. As the velocity increases, upward drag forces on the particles increase and at a stage become equal to the gravitational forces beneath. Hence the bed is said to be fluidized and the particles are suspended in the fluid.
In a fluid bed dryer used for powder drying, initially the air is sucked inside from the surroundings with a fan run with electric motor inside the dryer. The air then passes through heating system within the dryer and gets heated up. This hot drying air is then made to flow through bed of the moist materials that are laid on shaking perforated steel bed. This air is introduced with required velocity and temperature that the bed gets fluidized allowing intimate contact of each particle with the air. As the bed vibrates or shakes, the particles in the bed are carried forward slowly along the length of the dryer. All the moisture present in particles get sucked by the hot air which then escapes into the dust recovery system and is recycled for the further use in process. The velocity and temperature of air can be controlled as the particles pass on the bed and hence very wet to sticky materials can also be dried with a fluid bed dryer effectively. The dried material is then fed into the cooling zone where cool air reduces the temperature of the material to the required state. Therefore in this way product or powder drying can be efficiently achieved with the help of a fluid bed dryer.
Types of Fluidized Bed Dryers:
Dryers are planned as a complex system according to grain size, density, flow rate and inlet and outlet moisture values.
- Fluidized Bed Dryer - Special perforated distributor plate, continuous feed type, very high heat and mass transfer. Drying ,heating and cooling at the outlet occur on the same device.
- Heat Generator- By heating the air, it is evaporated by heat indirectly. Toxic materials are dried without problems.
- Coolant / Dehumidifier / Reheater - Conditioning the inlet cooling air.
- Product Feeder - Adjustable feeds on demand
- Fan 1 - Fluidized-bed air-flow fan that heats and dries in the Heat Generator
- Fan 3- Bag Filter suction and exhaust fan
- Dried material transport system (optional)